There are many applications, ranging from consumer electronics to telecommunications and the like, in which electrically-driven devices (e.g., electronic devices such as semiconductor-based integrated circuits) capable of performing various tasks are packed in close proximity in a small form factor to serve various needs. Such electrically-driven devices may include, for example, driver circuits, microprocessors, graphics processors, memory chips, global positioning system (GPS) chips, communications chips, laser diodes including edge-emitting lasers and vertical-cavity surface-emitting lasers (VCSELs), light-emitting diodes (LEDs), photodiodes, sensors, etc. Many of such electrically-driven devices inevitably generate thermal energy, or heat, in operation and thus are heat sources during operation as well as for a period of time after power off. As the number and complexity of the functionalities performed by such electrically-driven devices continue to increase and as the distance between electrically-driven devices in the small form factor continues to decrease, heat generated by such electrically-driven devices, as heat sources, present technical challenges that need to be addressed.
For one thing, performance, useful lifespan, or both, of an electrically-driven device may be significantly impacted if the heat generated by the device is not adequately dissipated or otherwise removed from the device. Moreover, in many present-day applications, given the close proximity between two or more electrically-driven devices on the same substrate, e.g., printed circuit board (PCB), a phenomenon of thermal coupling between the two or more devices in close proximity may occur and result in the heat generated by one of the devices being transferred to one or more adjacent devices. When thermal coupling occurs, at least a portion of the heat generated by a first electrically-driven device is transferred to a second electrically-driven device in close proximity due to temperature gradient, such that the temperature of the second electrically-driven device rises to a point higher than it would be when no heat is transferred from the first electrically-driven device to the second electrically-driven device. More specifically, when thermal coupling occurs and when no adequate heat transfer mechanism exists, heat generated by electrically-driven devices in close proximity may detrimentally deteriorate the performance and useful lifespan of some or all of the affected devices. As electrically-driven devices generate heat, they are referred to as heat-generating devices hereinafter.
Metal heat sinks or radiators, based on copper or aluminum for example, have been a dominant heat sink choice for electronics or photonics applications. As the form factor of electronic components (e.g., integrated circuits or IC) gets smaller it is impractical to build a small metal heat sink with a large surface area heat sink. Other problems associated with metal heat sinks include, for example, difficulty in precision alignment in mounting laser diode bars, VCSELs, LEDs or chips in laser diode/VCSEL/LED cooling applications, issues with overall compactness of the package, corrosion of the metallic material in water-cooled applications, difficulty in manufacturing, high-precision fabrication, electrical isolation, etc. Yet, increasing demand for higher power density in small form factor motivates the production of a compact cooling package with fewer or none of the aforementioned issues. Moreover, conventional packages typically use wire bonding to provide electrical power to the electrically-driven device(s) being cooled, but wire bonding may add cost and complexity in manufacturing and may be prone to defects in addition to occupying space unnecessarily.